What is concerned here is the evaluation of the transmitted signals (output signals) of a probe system, which, on a measuring probe, has a probe element that is deflectable out of its rest position and which, in response to a deflection of the probe element out of its rest position, generates a switch-on signal. Probe systems of this kind are used for determining the position of workpieces which are clamped in material-working machines, such as milling machines. The rest position of the probe element is understood to be a position in which the probe element does not have any contact with a workpiece. When the probe element makes contact with the workpiece, it is deflected out of its rest position.
To determine whether the probe element is deflected out of its rest position, a suitable detector system is used, and, as a function of the signals generated on the part of this detector system, the probe system delivers its transmission signals. Reference is made to German Published Patent Application No. 101 32 554.
In so-called wireless probe systems, the relevant switch-on signal is transmitted as an electromagnetic signal, e.g., as an infrared signal, to a receiving unit. In this receiving unit, the transmitted signals of the probe system are analyzed in order to ascertain the occurrence of switch-on signals (thus a deflection of the probe element). In this connection, in order to be able to differentiate the switch-on signal (and, if indicated, other relevant transmitted signals of the probe system, such as a battery signal) from interference signals (caused, for example, by the infrared component of dimmed neon tubes), the signals (received signals) received by the receiving unit are compared to a reference signal, and only those signals which exceed a signal threshold defined by the reference signal are further processed. Such a method and a corresponding circuit arrangement are described in International Published Patent Application No. WO 99/41856.
In this context, it is becoming increasingly more difficult to distinguish between transmitted signals of the probe system relevant to the analysis, and interference signals, because a data exchange between the probe system and the corresponding receiving unit is required over ever greater distances and, associated with this is also often a corresponding enlargement of the solid angle within which the transmitted signals are radiated.
It is an aspect of the present invention to provide a method and a system of the type mentioned at the outset, which may provide an enhanced differentiation between transmitted signals of the probe system and interference signals.